ExtremeProgramming is more than just a collection of 12 best practices. Even when all the practices are followed to the letter, subtle things such as thinking really simple or radically different can still escape the team. One of the things that an XP coach does is - to challenge existing assumptions. This is one of the reasons that an XP team usually succeeds in getting the job done in an elegant manner.
A lot of this philosophy seems to come from the idea of LateralThinking, that has been around for a while. EdwardDeBono's classic written in the 1970's seems to echo the philosophy we hear in XP today.
Some of the principles of LateralThinking are :
-- SomikRaha
Note that these principles do not suggest that you regularly throw out all existing practices. It's more a matter of regularly asking yourself, "Is this the best option?"
LateralThinking suggests that asking the question "Is this the best option" regularly is a bad idea - it restricts you to vertical thinking all the time. Thinking laterally is about having the freedom to be wrong, and from that wrong - you could get some brilliant rights (or not). In the book "Selling the Invisible", by Harry Beckwith, the author suggests that there is no perfect plan, "experts" get it wrong all the time. What is important is to start with something, and not be afraid to be wrong.
-- SomikRaha